The rolling chaparral and dramatic rock faces of Pinnacles National Monument inspire loyalty in visitors, from picnickers to rock-climbers and from stargazers to cave explorers. Pinnacles is visually stunning, as anyone who has seen the smooth orb of the moon glide from behind the crags of the High Peaks can attest, or who has watched the flashing black and white wings of acorn woodpeckers as they tuck acorns into the thick bark of gray pines. This striking beauty is attributable, in part, to the Monument’s geologic formations, showcase chaparral habitat, finely intergraded ecosystems and protected native plant and animal diversity. Another special Pinnacles quality is its proximity to millions of people.
Introduction
Established in 1908 to preserve the incongruent and beautiful rock formations for which it is named, the Pinnacles National Monument originally protected only 2,060 acres. It now encompasses 24,265 acres in the southern portion of the Gabilan Mountains, one of a series of parallel northwest-trending ridges and valleys that make up the Central Coast Range. Within the monument’s boundaries lie 24,000 acres of diverse wildlands. The monument is renowned for the beauty and variety of its spring wildflowers. A rich diversity of wildlife can be observed throughout the year.
Pinnacles National Monument is divided into East and West Districts that are connected by trails, but not by a vehicle road. More than 30 miles of trails access geological formations, spectacular vistas and wildland communities. The Pinnacles’ rock formations are a popular destination to challenge technical climbers. Pinnacles is a day-use park, but occasionally offers full moon hikes and dark sky astronomical observations led by ranger-interpreters.
Pinnacles National Monument, located near the San Andreas Fault along the boundary of the Pacific Plate and the North American Plate, is an excellent example of tectonic plate movement. The Pinnacles Rocks are believed to be part of the Neenach Volcano that occurred 23 million years ago near present-day Lancaster, California, some 195 miles (314 km) southeast. The giant San Andreas Fault split the volcano and the Pacific Plate crept north, carrying the Pinnacles. The work of water and wind on these erodible volcanic rocks has formed the unusual rock structures seen today.
Nature & Science
The faults within the Pinnacles National Monument mark distinct boundaries in geology. The Pinnacles Fault juxtaposes granitic basement rock west of the fault and the Pinnacles Volcanic Formation east of the fault. The Chalone Creek fault juxtaposes the Pinnacles Volcanic Formation west of the fault and the Temblor Fanglomerates east of the fault. The granitic basement is the Santa Lucia Granite and Granodiorite. These granites formed when masses of molten lava slowly cooled as they rose through the earth’s crust to a point where they completely solidified. A slow cooling process allows individual crystals to grow fairly large. Subsequent uplift from faulting and erosion of overlying material exposed these rocks at the earth’s surface. These are the oldest rocks in the park, 78-100 million years old. They form the basement upon which the rest of the rocks at the Monument lie.
The Pinnacles Volcanic Formation formed approximately 23 million years ago as it was extruded and deposited atop the granitic basement. The magma that was the source of all the volcanics was rhyolitic in origin. The formation consists of rocks such as banded and massive rhyolite, some andesites and dacites and various pyroclastic units.
The High Peaks consists of a relatively strong, well-consolidated breccia. The layers of breccias are thought to have formed as the result of material slumping off the sides of the volcano near the vents causing large landslides. The volcano was likely near water and the landslides traveled as massive turbidity currents under water that spread the material considerable distances until coming to rest near distant edges of the volcano. Volcanic ash and rhyolitic lava flows are interlayered with these breccias. Subsequent burial and compaction hardened these layers into the consolidated rock we see today. Recent faulting, fracturing and erosion have sculpted these rock layers into vertical cliffs and spires sometimes several hundred feet high.
The Temblor Formation east of the Chalone Creek Fault is a fanglomerate unit (conglomerates deposited in an alluvial fan setting) composed of granitic and to a lesser extent volcanic detritus shed from the Santa Lucia granitic basement and the Pinnacles Volcanics.
Recreation
The primary importance of Pinnacles National Monument is that of a natural preserve and recreational area. The main visitor uses of the park are hiking, technical rock climbing and as a place to study and observe the natural ecology of central California. Pinnacles has a rich flora and fauna and a complex and spectacular geology. Birding, wild flower walks and the study of volcanic and plate tectonics are popular activities.
Getting There
By Car
Pinnacles National Monument consists of two districts: east and west. The West District is accessible from Highway 101 near the town of Soledad, then east along Highway 146 to the Chaparral area.
The East District entrance is reached via Highway 25, south of the city of Hollister, then west on Highway 146.
Note: The districts are NOT connected by a road. It is not possible to drive through the Monument from one side to the other.
Traveler Facts
Contact Information
Pinnacles National Monument
5000 Highway 146
Paicines, CA 95043
Phone: 831-389-4485
Fax: 831-389-4489
Operating Hours & Seasons
The Pinnacles National Monument is open to day use every day of the year.
The east side of the Pinnacles is now open 24 hours a day for hiking. No overnight camping or backpacking is permitted.
Gates on the west side of the Pinnacles will continue to close each night. Winter hours are now in effect. The west entrance is open from 7:30 a.m. to 6:00 p.m.
Weather/Climate
Pinnacles National Monument has a Mediterranean climate of hot, dry summers and cool winters with moderate rainfall. Although the Monument is only 40 miles from the Pacific Ocean, the Santa Lucia Mountains to the west strongly modify the ocean influence before it reaches inland to Pinnacles. Consequently, while on the coast summer temperatures might be a fairly steady 60 degrees Fahrenheit, at Pinnacles the temperature can swing from 50 degrees at night to 100 degrees in the day. Similarly, due to the absence of the ocean’s warming effect, winter temperatures at Pinnacles often drop below freezing while coastal temperatures remain moderate. Average rainfall is 16 inches per year, falling mostly from January through March. Snow occurs in small amounts at higher elevations almost every year between mid-December and January.
